Heating and cooling refrigeration apparatus

ABSTRACT

Refrigerant is passed from a stage other than the last stage of a multistage centrifugal compressor to a waste heat condenser for liquefying refrigerant and returning it to a cooling load evaporator. The latent heat of the refrigerant, along with the heat of compression, is rejected to the atmosphere as by a cooling tower and interconnecting water circuit. There is capacity control means for regulating refrigerant flow from the evaporator to the compressor in accordance with the cooling load imposed on the evaporator. A line is provided for passing refrigerant vapor from the last stage of the compressor to a second condenser, which serves as a heat exchanger for heating a medium for satisfying a heating load demand. A refrigerant line extends from the second condenser to the first condenser. The compressor includes flow control means, as a diffuser sleeve valve, in the last stage operable to regulate the passage of refrigerant vapor to the second condenser in accordance to the heat load imposed thereon. A refrigerant vapor line including a flow control valve extends from the vapor area of the first condenser to the inlet of each stage of the compressor. The flow control valves are operated sequentially according to the pressure in the first condenser to provide a sufficient supply of refrigerant vapor for passage from the last compressor stage to the second condenser to satisfy the heat load impressed thereon.

United States Patent Anderson et al.

[54] HEATING AND COOLING REFRIGERATION APPARATUS [72] Inventors: Carl M.Anderson; William T. Osborne,

both of Syracuse, N.Y.

[73] Assignee: Carrier Corporation, Syracuse, N.Y.

[22] Filed: July 13, 1970 [21] Appl. No.: 54,176

Primary Examiner-Meyer Perlin Att0rneyHarry G. Martin, Jr. and J.Raymond Curtin 1 May 30,1972

[ ABSTRACT Refrigerant is passed from a stage other than the last stageof a multistage centrifugal compressor to a waste heat condenser forliquefying' refrigerant and returning it to a cooling load evaporator.The latent heat of the refrigerant, along with the heat of compression,is rejected to the atmosphere as by a cooling tower and interconnectingwater circuit. There is capacity control means for regulatingrefrigerant flow from the evaporator to the compressor in accordancewith the cooling load imposed on the evaporator. A line is provided forpassing refrigerant vapor from the last stage of the compressor to asecond condenser, which serves as a heat exchanger for heating a mediumfor satisfying a heating load demand. A refrigerant line extends fromthe second condenser to the first condenser. The compressor includesflow control means, as a diffuser sleeve valve, in the last stageoperable to regulate the passage of refrigerant vapor to the secondcondenser in accordance to the heat load imposed thereon. A refrigerantvapor line including a flow control valve extends from the vapor area ofthe first condenser to the inlet of each stage of the compressor. Theflow control valves are operated sequentially according to the pressurein the first condenser to provide a sufficient supply of refrigerantvapor for passage from the last compressor stage to the second condenserto satisfy the heat load impressed thereon.

7 Claims, 1 Drawing Figure OOOOOOOOOOO 00 0000000 000000000 Patented May30, 1972 O 0000 0000 O 00000 O0 O0 00 000000000 QOOOOOOOOQ INVENTORS.CARL M. ANDERSON BY mum/7y SBORNE ATTORNEY HEATING AND COOLINGREFRIGERATION APPARATUS BACKGROUND OF THE INVENTION In the co-pendingapplication of James W. Endress and Carl M. Anderson, Ser. No. 54,175filed July 13, 1970, there is disclosed an improved heating and coolingapparatus of the type which functions to simultaneously provide coolingto one portion of a building, such as the interior area of the building,and heating to another portion of the building, such as the peripheralarea. According to the invention disclosed in said application, amultistage centrifugal compressor is employed to provide refrigerantvapor from an intermediate stage of a compressor to a waste heatcondenser. The liquid refrigerant is passed from the condenser to anevaporator or liquid chiller. The refrigerant vapor return from theevaporator to the compressor includes means for varying the flow of therefrigerant vapor and therefore to vary the capacity of the compressoraccording to the coiling demand imposed on the system as determined by atemperature sensor on the outgoing chilled water line.

If the system is required to satisfy a heat load, the refrigerant vaporoutput from the last stage of the compressor is passed to a heatexchanger which includes a tube bundle connected to the hot waterheating circuit. The amount or volume of refrigerant vapor passed fromthe last stage of the compressor to the heat exchanger is in proportionto the heating demand.

The condensed liquid refrigerant in the heat exchanger is conveyed tothe waste heat condenser.

If the cooling load is relatively light and, simultaneously, there is ahigh heating demand load, the waste heat condenser serves in that caseas a flash economizer providing reverse flow of refrigerant vapor to theinlet of the last stage of the compressor. With this system, additionalrefrigerantvapor is supplied to the last stage of the compressor duringhigh heating demand, all whereby that system is capable of handling amuch higher heating demand load in ratio to the cooling demand thanobtained by prior arrangements.

SUMMARY OF THE INVENTION This invention is an improvement over thatdisclosed in the application above referred to in that a refrigerantvapor passage line is provided from the vapor area of the waste heatcondenser to the inlet of each stage of the compressor. Also, the liquidrefrigerant conveyed from the heating condenser is sprayed over the tubebundle in the waste heat condenser, effecting a more rapid and thoroughflashing of the liquid refrigerant with greater absorption of heat fromthe condensing water supplied to the waste heat condenser. Accordingly,an abundant supply of refrigerant vapor, at elevated temperature, ismade available for compression through selected stages of the compressorfor greater temperature rise in the second condenser to satisfy agreater heating demand. Each flow line for passage of refrigerant vaporfrom the condenser to each stage of the compressor includes a flowcontrol valve, and means is provided for operating these valvessequentially according to the pressure in the condenser to make certaina sufficient supply of refrigerant vapor is passed to the compressor fordischarge by the last stage to meet the heating demand. In other words,with the apparatus arrangement of our invention, the lift provided byall three stages of the compressor may be applied to the secondcondenser to handle a high heat load relative to a given cooling load.Accordingly, the heating to cooling capability of the apparatus canachieve a level of approximately L8 to 1.

BRIEF DESCRIPTION OF THE DRAWING The drawing is a schematic diagramillustrating the apparatus arrangement embodying our invention.

2 DESCRIPTION OF THE PREFERRED EMBODIMENT In the drawing, there isdisclosed a three stage compressor having impellers 10, 11, and 12operated by a driver 13. The cooling load imposed on the system ishandled by a cooling medium such as water or brine circulated in a tubebundle 15 mounted in a cooler shell 17. Refrigerant vapor is drawn fromthe cooler 17 through a line 20 to the inlet of the compressor. Capacitycontrol means 21, such as inlet guide vanes, are arranged at the inletto the compressor and are operated by a temperature sensor 23 affixed inheat exchanging relation to the output line 25 of the cooler.

A refrigerant vapor line 27 extends from the discharge of the secondstage 11 of the compressor to a waste heat condenser 30. The condenser30 includes a tube bundle 31 having an inlet line 33 extending from asource of cooling water such as a water tower. The return line isindicated at 35. A liquid refrigerant line 37 extends to a float controlmetering valve mechanism 40 from which liquid refrigerant is dischargedthrough line 41 to the cooler 17. This portion of the equipmentfunctions in conventional manner as a two stage centrifugal compressorrefrigeration system.

A line 45 extends from the discharge of the third compressor stage 12 toa heat exchanger 47. The heat exchanger is provided with a tube bundle50 through which a medium for carrying away heat, such as water, iscirculated, the inlet line 53 and outlet line 54 being connected to theheating circuit. Refrigerant is discharged from the heat exchanger 47 tothe float control mechanism 60 by line 61, and a line 62 extends to thewaste heat condenser 30.

Heating demand is sensed by a temperature responsive device 63 attachedto the line 54 through which the heating medium leaves the heatexchanger 47. The sensor 63 is con nected by a line 65 to an actuator 67which operates a flow control means, such as a diffuser valve 70, tocontrol the passage of refrigerant vapor from the third stage of thecompressor to the heat exchanger 47. The diffuser valve 70 is movedbetween open and closed positions in proportion to the heat load imposedon the tube bundle 50 as determined by the sensor 63. The refrigerantvapor line 27 includes a flow control valve which, in the absence of aheating load of predetermined value on heat exchanger 47, is in openposition to provide the flow of refrigerant vapor from the secondcompressor stage 11 to the wasteheat condenser 30 to reject the heat ofcompression and the latent heat of the refrigerant.

The apparatus also includes a line 76 extending from the discharge ofthe first stage of the compressor to the waste heat condenser 30, and aline 77 extending from the waste heat condenser 30 to the inlet of thecompressor. A flow control valve 78 is connected in the line 76, and asimilar valve 79 is connected in line 77. The valves 78,79 are closeduntil the heating load on the exchanger 47 reaches a predeterminedvalue.

If the sensor 63 senses a temperature of the water in the tube bundle50, indicating the existence of a heating requirement for the outer orperipheral portion of the building, the diffuser valve 70 will be movedtoward open position for the flow of refrigerant vapor through the line45. As the diffuser valve 70 of the third compressor stage moves to awider open position and the pressure in the heating condenser falls asit supplies heat to the water leaving at 54, the pressure between stages2 and 3 of the compressor falls to the point at which all of the flowdischarging from the second state passes on to the third stage, and norefrigerant vapor flow travels through line 27 to the condenser 30.However, a given water chilling load imposed on the cooler 17 issatisfied by the flow of liquid refrigerant through line 37, meteringvalve 40, and line 41. Under this situation, the condenser 30 is beingsupplied with refrigerant from heat exchanger 47 through lines 61,62.

The line 62 terminates in a supply header 80 arranged in the waste heatcondenser 30 and is effective to disperse the refrigerant on the tubebundle 31, whereby the condenser 30 serves as a flash economizer toprovide an adequate supply of refrigerant vapor to the last compressorstage to handle a high heating load.

lf the hot water heating load demand further increases, the diffusersleeve valve 70 opens still further, whereupon the refrigerant from line62 that is wetting the tube bundle 31 in condenser 30 by being sprayedon the tube bundle boils, thereby drawing heat from the cooling towerwater line 33,35. Refrigerant vapor accordingly passes from the wasteheat condenser 30 in reverse flow as indicated by the arrow 81 throughthe then open valve 75 to be compressed and again condensed in the heatexchanger 47. Under these operating conditions, a heating to coolingratio of approximately 1.2 to 1 may be obtained.

However, if there is still further reduction in the outside airtemperature, with increase in heat load demand, and accordingly areduction in the temperature of cooling tower water supplied to wasteheat condenser 30, the pressure in the waste heat condenser 30 may dropbelow the suction pressure intermediate the second and third compressorstages with reduction of available refrigerant vapor flow from thecondenser 30 to the inlet of the third compressor stage. Means isprovided for sensing the pressure in the waste heat condenser 30.Inasmuch as condenser pressure and temperature are substantiallysynonomous, the condenser pressure may be determined by a temperaturesensor 93 attached to the incoming water line 33. The sensor 93 is of aconventional type having contacts operable sequentially according to thesensed temperature. The output of the sensor 93 is passed to the valves75,78,79 through cable 95 in which there is connected a relay orswitching device 96 controlled by the sensor 63 through line 97.

The contacts of the relay 96 are open when the sensor 63 does not sensethe presence of a heating demand above a predetermined value. In thissituation, the valve 75 as previously stated is in open position; andthe valves 78,79 are closed. Upon sensor 63 sensing a heating loaddemand above thepredetermined value, the valves 75,78,79 are placedunder the control of the sensor 93. The arrangement is such that whenthe pressure within waste heat condenser 30 drops below the suctionpressure between stages 2 and 3 of the compressor, the sensor 93actuates the valve 75 to closed position and the valve 78 to openposition. This results in a flow of refrigerant vapor from the condenser30 through line 76 to the inlet of the second compressor stage impeller1 1. Accordingly, the increase in heating load is readily satisfied bythe lift obtained from the second and third stages of the compressor. Inlike manner, with still further reduction in outside temperature, with aproportionately greater heating load placed on the heat exchanger 47,and with a further reduction of pressure in condenser 30, valve 78 isclosed and valve 79 in line 77 is opened.

In the absence of any heating load, the diffuser volume control valve 70does not close entirely tight as will be understood by those familiarwith centrifugal compressor operation. To prevent over-pressurizing theheat exchanger 47 during extended periods when there is no heatingdemand load, the float valve mechanism 60 may be shunted by a branchline 100 in which an orifice 101 is connected. The orifice 101 isdimensioned to pass a sufficient flow of refrigerant from the heatexchanger to the condenser 30 to prevent the buildup of an undesirablyhigh pressure in the heat exchanger and overheating of the lastcompressor stage.

With valves 75, 78 closed and valve 79 in line 77 open, all stages ofthe compressor now impart lift to the refrigerant vapor through line 45which is significantly greater in volume than that supplied by line 20,whereby the system is capable of producing a heating to cooling ratio ofapproximately 1.8 to l.

The apparatus arrangement of the system embodying our invention rendersit particularly suitable for installation in smaller building unitswhere internal zone cooling loads are much smaller than the heatingrequirements in the spring and fall seasons.

We claim:

1. Apparatus for simultaneously satisfying heating and cooling demandsin a building comprising a multistage compressor, a waste heatcondenser, and a cooling load evaporator connected to form a circuitincluding a refrigerant vapor line extending between each stage of saidcompressor, other than the last stage thereof, and said waste heatcondenser, a first liquid refrigerant passage including flow meteringmeans extending from saidwaste heat condenser to said evaporator,cooling capacity control means regulating the How of refrigerant vaporfrom said evaporator to the inlet of said compressor in accordance withthe cooling load demand imposed on said apparatus, a heat exchanger, arefrigerant vapor passage extending from the discharge of the last stageof said compressor to said heat exchanger, means for circulating waterto be heated for satisfying a heating load demand in heat exchangingrelation to the refrigerant in said heat exchanger, a second liquidrefrigerant passage including flow metering means extending from saidheat exchanger to said waste heat condenser, refrigerant flow controlmeans for regulating the flow of refrigerant vapor from said last stageto said heat exchanger according to the heating load demand imposed onsaid heat exchanger, a flow control valve in each of said refrigerantvapor lines, one of said valves being opened in the absence of a heatingload imposed on said heat exchanger and the others of said valves beingclosed, flow control valve operating means associated with said wasteheat condenser and operable upon the presence of a heating load on saidheat exchanger to selectively open and close said flow control valves insaid refrigerant vapor lines according to the pressure in said wasteheat condenser.

2. Apparatus as set forth in claim 1 wherein said waste heat condenserincludes a tube bundle containing a cooling medium, a refrigerant spraymeans connected to said second liquid refrigerant passage means andoperable to spray the liquid refrigerant on said tube bundle.

3. Apparatus as set forth in claim 1 wherein said waste heat condenserincludes a tube bundle containing a cooling medium, said flow controlvalve operating means including a temperature sensor responsive to thetemperature of said cooling medium in said tube bundle.

4. Apparatus as set forth in claim 1 wherein said refrigerant flowcontrol means for regulating the flow of refrigerant vapor from saidlast compressor stage includes a temperature sensor responsive to thetemperature of the circulating water in said heat exchanger.

5. Apparatus as set forth in claim 1 wherein said flow control means forregulating the flow of refrigerant vapor from said last compressor stageincludes a temperature sensor responsive to the temperature of thecirculating water leaving said heat exchanger.

6. Apparatus as set forth in claim 1 wherein said refrigerant flowcontrol means for regulating the flow of refrigerant from said lastcompressor stage includes a diffuser valve operable to vary the flow ofrefrigerant from said last compressor stage, and a temperature sensorresponsive to the temperature of said circulating water in said heatexchanger for operating said difiuser valve.

7. Apparatus as set forth in claim 1 wherein said one flow control valveopened in the absence of a heating load imposed on said heat exchangerbeing in the refrigerant vapor line extending from next to the laststage of said compressor to said waste heat condenser.

1. Apparatus for simultaneously satisfying heating and cooling demandsin a building comprising a multistage compressor, a waste heatcondenser, and a cooling load evaporator connected to form a circuitincluding a refrigerant vapor line extending between each stage of saidcompressor, other than the last stage thereof, and said waste heatcondenser, a first liquid refrigerant passage including flow meteringmeans extending from said waste heat condenser to said evaporator,cooling capacity control means regulating the flow of refrigerant vaporfrom said evaporator to the inlet of said compressor in accordance withthe cooling load demand imposed on said apparatus, a heat exchanger, arefrigerant vapor passage extending from the discharge of the last stageof said compressor to said heat exchanger, means for circulating waterto be heated for satisfying a heating load demand in heat exchangingrelation to the refrigerant in said heat exchanger, a second liquidrefrigerant passage including flow metering means extending from saidheat exchanger to said waste heat condenser, refrigerant flow controlmeans for regulating the flow of refrigerant vapor from said last stageto said heat exchanger according to the heating load demand imposed onsaid heat exchanger, a flow control valve in each of said refrigerantvapor lines, one of said valves being opened in the absence of a heatingload imposed on said heat exchanger and the others of said valves beingclosed, flow control valve operating means associated with said wasteheat condenser and operable upon the presence of a heating load on saidheat exchanger to selectively open and close said flow control valves insaid refrigerant vapor lines according to the pressure in said wasteheat condenser.
 2. Apparatus as set forth in claim 1 wherein said wasteheat condenser includes a tube bundle containing a cooling medium, arefrigerant spray Means connected to said second liquid refrigerantpassage means and operable to spray the liquid refrigerant on said tubebundle.
 3. Apparatus as set forth in claim 1 wherein said waste heatcondenser includes a tube bundle containing a cooling medium, said flowcontrol valve operating means including a temperature sensor responsiveto the temperature of said cooling medium in said tube bundle. 4.Apparatus as set forth in claim 1 wherein said refrigerant flow controlmeans for regulating the flow of refrigerant vapor from said lastcompressor stage includes a temperature sensor responsive to thetemperature of the circulating water in said heat exchanger. 5.Apparatus as set forth in claim 1 wherein said flow control means forregulating the flow of refrigerant vapor from said last compressor stageincludes a temperature sensor responsive to the temperature of thecirculating water leaving said heat exchanger.
 6. Apparatus as set forthin claim 1 wherein said refrigerant flow control means for regulatingthe flow of refrigerant from said last compressor stage includes adiffuser valve operable to vary the flow of refrigerant from said lastcompressor stage, and a temperature sensor responsive to the temperatureof said circulating water in said heat exchanger for operating saiddiffuser valve.
 7. Apparatus as set forth in claim 1 wherein said oneflow control valve opened in the absence of a heating load imposed onsaid heat exchanger being in the refrigerant vapor line extending fromnext to the last stage of said compressor to said waste heat condenser.